Striated Condensate Drain Pan

ABSTRACT

A heating, ventilation, and/or air conditioning (HVAC) system is provided. The HVAC system includes at least one heat exchanger, and a drain pan disposed at least partially around a downstream end of the at least one heat exchanger, wherein the drain pan comprises a fluted surface configured to direct condensate flowing from the at least one heat exchanger into a concavity within the drain pan.

CROSS-REFERENCE TO RELATED APPLICATIONS

Not applicable.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

REFERENCE TO A MICROFICHE APPENDIX

Not applicable.

BACKGROUND

Heating, ventilation, and/or air conditioning (HVAC) systems may generally be used in residential and/or commercial areas for heating and/or cooling to create comfortable temperatures inside those areas. Some HVAC systems may be split-type heat pump systems that have an indoor and outdoor unit and are capable of cooling a comfort zone by operating in a cooling mode for transferring heat from a comfort zone to an ambient zone using a refrigeration cycle and also generally capable of reversing the direction of refrigerant flow through the components of the HVAC system so that heat is transferred from the ambient zone to the comfort zone, thereby heating the comfort zone. Such split-type heat pump systems commonly use an inclined heat exchanger as the indoor heat exchanger due to characteristics such as efficient performance, compact size, and cost effectiveness.

SUMMARY

In some embodiments of the disclosure, a heating, ventilation, and/or air conditioning (HVAC) system is disclosed. The HVAC system includes at least one heat exchanger, and a drain pan disposed at least partially around a downstream end of the at least one heat exchanger, wherein the drain pan comprises a fluted surface configured to direct condensate flowing from the at least one heat exchanger into a concavity within the drain pan.

In other embodiments of the disclosure, an air handling unit is disclosed. The air handling unit includes at least one heat exchanger, and a drain pan disposed at least partially around a downstream end of the at least one heat exchanger, wherein the drain pan comprises a fluted surface configured to direct condensate flowing from the at least one heat exchanger into a concavity within the drain pan.

For the purpose of clarity, any one of the embodiments disclosed herein may be combined with any one or more other embodiments disclosed herein to create a new embodiment within the scope of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure and the advantages thereof, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description:

FIG. 1 is a schematic diagram of an HVAC system according to an embodiment of the disclosure;

FIG. 2 is a schematic diagram of an air handling unit according to an embodiment of the disclosure;

FIG. 3 is a schematic diagram of an air handling unit according to another embodiment of the disclosure;

FIG. 4 depicts an example of a water droplet on a conventional drain and a water droplet on a drain pan according to embodiments of the disclosure;

FIG. 5 is a schematic diagram of a drain pan according to an embodiment of the disclosure;

FIG. 6A is a schematic diagram of a drain pan according to another embodiment of the disclosure;

FIG. 6B is an example of a fluted surface on the drain pan depicted in FIG. 6A;

FIG. 7 depicts a graph illustrating the physics of water blow-off on a conventional drain pan; and

FIG. 8 depicts a graph illustrating the physics of water blow-off on a drain pan according to embodiments of the disclosure.

DETAILED DESCRIPTION

It should be understood at the outset that although illustrative implementations of one or more embodiments of the present disclosure are provided below, the disclosed systems and/or methods may be implemented using any number of techniques, whether currently known or in existence. The disclosure should in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, including the exemplary designs and implementations illustrated and described herein, but may be modified within the scope of the appended claims along with their full scope of equivalents.

In an HVAC system including a heat exchanger configured to cool and/or dehumidify air, a drain pan may be used to collect and remove condensed water formed on an evaporator coil during operation of the heat exchanger. Such drain pans are typically constructed from plastic. Due to the non-polar nature of the long hydrocarbon chains that make up their plastic resins, the surface of drain pans tends to be somewhat hydrophobic such that water may repel upon contact. For example, the contact angle of a water droplet on the surface of a drain pan may be about 90 degrees or more. In areas where the drain pan may be exposed to air flowing through the heat exchanger at relatively high velocities, an issue known as “water blow-off” may occur. That is, water droplets at or near such areas may inadvertently become swept from the drain pan and protrude into the airstream, where water may accumulate and potentially cause damage. For example, water may be swept into ductwork and cause one or more ducts to harbor biological growth (e.g., mold, fungus, or algae), which may damage surrounding areas such as an attic, wall insulation, building structural elements, ceilings, carpets, personal belongings, etc. To mitigate and prevent such damage, embodiments of the present disclosure provide a drain pan comprising a plurality of dimensionally optimized striations configured to drain condensate before being exposed to high velocity airflow.

Referring now to FIG. 1, a schematic diagram of an HVAC system 100 is shown according to an embodiment of the disclosure. Most generally, HVAC system 100 comprises a heat pump system that may be selectively operated to implement one or more substantially closed thermodynamic refrigeration cycles to provide a cooling functionality (hereinafter “cooling mode”) and/or a heating functionality (hereinafter “heating mode”). The HVAC system 100, configured as a heat pump system, generally comprises an indoor unit 102, an outdoor unit 104, and a system controller 106 that may generally control operation of the indoor unit 102 and/or the outdoor unit 104.

Indoor unit 102 generally comprises an indoor air handling unit comprising an indoor heat exchanger 108, an indoor fan 110, an indoor metering device 112, and an indoor controller 124. The indoor heat exchanger 108 may generally be configured to promote heat exchange between refrigerant carried within internal tubing of the indoor heat exchanger 108 and an airflow that may contact the indoor heat exchanger 108 but that is segregated from the refrigerant. In some embodiments, the indoor heat exchanger 108 may comprise a plate-fin heat exchanger. However, in other embodiments, indoor heat exchanger 108 may comprise a microchannel heat exchanger and/or any other suitable type of heat exchanger.

The indoor fan 110 may generally comprise a centrifugal blower comprising a blower housing, a blower impeller at least partially disposed within the blower housing, and a blower motor configured to selectively rotate the blower impeller. The indoor fan 110 may generally be configured to provide airflow through the indoor unit 102 and/or the indoor heat exchanger 108 to promote heat transfer between the airflow and a refrigerant flowing through the indoor heat exchanger 108. The indoor fan 110 may also be configured to deliver temperature-conditioned air from the indoor unit 102 to one or more areas and/or zones of a climate controlled structure. The indoor fan 110 may generally comprise a mixed-flow fan and/or any other suitable type of fan. The indoor fan 110 may generally be configured as a modulating and/or variable speed fan capable of being operated at many speeds over one or more ranges of speeds. In other embodiments, the indoor fan 110 may be configured as a multiple speed fan capable of being operated at a plurality of operating speeds by selectively electrically powering different ones of multiple electromagnetic windings of a motor of the indoor fan 110. In yet other embodiments, however, the indoor fan 110 may be a single speed fan.

The indoor metering device 112 may generally comprise an electronically-controlled motor-driven electronic expansion valve (EEV). In some embodiments, however, the indoor metering device 112 may comprise a thermostatic expansion valve, a capillary tube assembly, and/or any other suitable metering device. In some embodiments, while the indoor metering device 112 may be configured to meter the volume and/or flow rate of refrigerant through the indoor metering device 112, the indoor metering device 112 may also comprise and/or be associated with a refrigerant check valve and/or refrigerant bypass configuration when the direction of refrigerant flow through the indoor metering device 112 is such that the indoor metering device 112 is not intended to meter or otherwise substantially restrict flow of the refrigerant through the indoor metering device 112.

Outdoor unit 104 generally comprises an outdoor heat exchanger 114, a compressor 116, an outdoor fan 118, an outdoor metering device 120, a reversing valve 122, and an outdoor controller 126. In some embodiments, the outdoor unit 104 may also comprise a plurality of temperature sensors for measuring the temperature of the outdoor heat exchanger 114, the compressor 116, and/or the outdoor ambient temperature. The outdoor heat exchanger 114 may generally be configured to promote heat transfer between a refrigerant carried within internal passages of the outdoor heat exchanger 114 and an airflow that contacts the outdoor heat exchanger 114 but that is segregated from the refrigerant. In some embodiments, outdoor heat exchanger 114 may comprise a plate-fin heat exchanger. However, in other embodiments, outdoor heat exchanger 114 may comprise a spine-fin heat exchanger, a microchannel heat exchanger, or any other suitable type of heat exchanger.

The compressor 116 may generally comprise a variable speed scroll-type compressor that may generally be configured to selectively pump refrigerant at a plurality of mass flow rates through the indoor unit 102, the outdoor unit 104, and/or between the indoor unit 102 and the outdoor unit 104. In some embodiments, the compressor 116 may comprise a rotary type compressor configured to selectively pump refrigerant at a plurality of mass flow rates. In alternative embodiments, however, the compressor 116 may comprise a modulating compressor that is capable of operation over a plurality of speed ranges, a reciprocating-type compressor, a single speed compressor, and/or any other suitable refrigerant compressor and/or refrigerant pump. In some embodiments, the compressor 116 may be controlled by a compressor drive controller 144, also referred to as a compressor drive and/or a compressor drive system.

The outdoor fan 118 may generally comprise an axial fan comprising a fan blade assembly and fan motor configured to selectively rotate the fan blade assembly. The outdoor fan 118 may generally be configured to provide airflow through the outdoor unit 104 and/or the outdoor heat exchanger 114 to promote heat transfer between the airflow and a refrigerant flowing through the indoor heat exchanger 108. The outdoor fan 118 may generally be configured as a modulating and/or variable speed fan capable of being operated at a plurality of speeds over a plurality of speed ranges. In other embodiments, the outdoor fan 118 may comprise a mixed-flow fan, a centrifugal blower, and/or any other suitable type of fan and/or blower, such as a multiple speed fan capable of being operated at a plurality of operating speeds by selectively electrically powering different multiple electromagnetic windings of a motor of the outdoor fan 118. In yet other embodiments, the outdoor fan 118 may be a single speed fan. Further, in other embodiments, however, the outdoor fan 118 may comprise a mixed-flow fan, a centrifugal blower, and/or any other suitable type of fan and/or blower.

The outdoor metering device 120 may generally comprise a thermostatic expansion valve. In some embodiments, however, the outdoor metering device 120 may comprise an electronically-controlled motor driven EEV similar to indoor metering device 112, a capillary tube assembly, and/or any other suitable metering device. In some embodiments, while the outdoor metering device 120 may be configured to meter the volume and/or flow rate of refrigerant through the outdoor metering device 120, the outdoor metering device 120 may also comprise and/or be associated with a refrigerant check valve and/or refrigerant bypass configuration when the direction of refrigerant flow through the outdoor metering device 120 is such that the outdoor metering device 120 is not intended to meter or otherwise substantially restrict flow of the refrigerant through the outdoor metering device 120.

The reversing valve 122 may generally comprise a four-way reversing valve. The reversing valve 122 may also comprise an electrical solenoid, relay, and/or other device configured to selectively move a component of the reversing valve 122 between operational positions to alter the flow path of refrigerant through the reversing valve 122 and consequently the HVAC system 100. Additionally, the reversing valve 122 may also be selectively controlled by the system controller 106 and/or an outdoor controller 126.

The system controller 106 may generally be configured to selectively communicate with an indoor controller 124 of the indoor unit 102, an outdoor controller 126 of the outdoor unit 104, and/or other components of the HVAC system 100. In some embodiments, the system controller 106 may be configured to control operation of the indoor unit 102 and/or the outdoor unit 104. In some embodiments, the system controller 106 may be configured to monitor and/or communicate with a plurality of temperature sensors associated with components of the indoor unit 102, the outdoor unit 104, and/or the ambient outdoor temperature. Additionally, in some embodiments, the system controller 106 may comprise a temperature sensor and/or may further be configured to control heating and/or cooling of zones associated with the HVAC system 100. In other embodiments, however, the system controller 106 may be configured as a thermostat for controlling the supply of conditioned air to zones associated with the HVAC system 100.

The system controller 106 may also generally comprise an input/output (I/O) unit (e.g., a graphical user interface, a touchscreen interface, or the like) for displaying information and for receiving user inputs. The system controller 106 may display information related to the operation of the HVAC system 100 and may receive user inputs related to operation of the HVAC system 100. However, the system controller 106 may further be operable to display information and receive user inputs tangentially and/or unrelated to operation of the HVAC system 100. In some embodiments, however, the system controller 106 may not comprise a display and may derive all information from inputs from remote sensors and remote configuration tools.

In some embodiments, the system controller 106 may be configured for selective bidirectional communication over a communication bus 128. In some embodiments, portions of the communication bus 128 may comprise a three-wire connection suitable for communicating messages between the system controller 106 and one or more of the HVAC system 100 components configured for interfacing with the communication bus 128. Still further, the system controller 106 may be configured to selectively communicate with HVAC system 100 components and/or any other device 130 via a communication network 132. In some embodiments, the communication network 132 may comprise a telephone network, and the other device 130 may comprise a telephone. In some embodiments, the communication network 132 may comprise the Internet, and the other device 130 may comprise a smartphone and/or other Internet-enabled mobile telecommunication device. In other embodiments, the communication network 132 may also comprise a remote server.

The indoor controller 124 may be carried by the indoor unit 102 and may generally be configured to receive information inputs, transmit information outputs, and/or otherwise communicate with the system controller 106, the outdoor controller 126, and/or any other device 130 via the communication bus 128 and/or any other suitable medium of communication. In some embodiments, the indoor controller 124 may be configured to communicate with an indoor personality module 134 that may comprise information related to the identification and/or operation of the indoor unit 102. In some embodiments, the indoor controller 124 may be configured to receive information related to a speed of the indoor fan 110, transmit a control output to an electric heat relay, transmit information regarding an indoor fan 110 volumetric flow-rate, communicate with and/or otherwise affect control over an air cleaner 136, and communicate with an indoor EEV controller 138. In some embodiments, the indoor controller 124 may be configured to communicate with an indoor fan controller 142 and/or otherwise affect control over operation of the indoor fan 110. In some embodiments, the indoor personality module 134 may comprise information related to the identification and/or operation of the indoor unit 102 and/or a position of the outdoor metering device 120.

The indoor EEV controller 138 may be configured to receive information regarding temperatures and/or pressures of the refrigerant in the indoor unit 102. More specifically, the indoor EEV controller 138 may be configured to receive information regarding temperatures and pressures of refrigerant entering, exiting, and/or within the indoor heat exchanger 108. Further, the indoor EEV controller 138 may be configured to communicate with the indoor metering device 112 and/or otherwise affect control over the indoor metering device 112. The indoor EEV controller 138 may also be configured to communicate with the outdoor metering device 120 and/or otherwise affect control over the outdoor metering device 120.

The outdoor controller 126 may be carried by the outdoor unit 104 and may be configured to receive information inputs, transmit information outputs, and/or otherwise communicate with the system controller 106, the indoor controller 124, and/or any other device 130 via the communication bus 128 and/or any other suitable medium of communication. In some embodiments, the outdoor controller 126 may be configured to communicate with an outdoor personality module 140 that may comprise information related to the identification and/or operation of the outdoor unit 104. In some embodiments, the outdoor controller 126 may be configured to receive information related to an ambient temperature associated with the outdoor unit 104, information related to a temperature of the outdoor heat exchanger 114, and/or information related to refrigerant temperatures and/or pressures of refrigerant entering, exiting, and/or within the outdoor heat exchanger 114 and/or the compressor 116. In some embodiments, the outdoor controller 126 may be configured to transmit information related to monitoring, communicating with, and/or otherwise affecting control over the compressor 116, the outdoor fan 118, a solenoid of the reversing valve 122, a relay associated with adjusting and/or monitoring a refrigerant charge of the HVAC system 100, a position of the indoor metering device 112, and/or a position of the outdoor metering device 120. The outdoor controller 126 may further be configured to communicate with and/or control a compressor drive controller 144 that is configured to electrically power and/or control the compressor 116.

The HVAC system 100 is shown configured for operating in a so-called heating mode in which heat may generally be absorbed by refrigerant at the outdoor heat exchanger 114 and rejected from the refrigerant at the indoor heat exchanger 108. Starting at the compressor 116, the compressor 116 may be operated to compress refrigerant and pump the relatively high temperature and high pressure compressed refrigerant through the reversing valve 122 and to the indoor heat exchanger 108, where the refrigerant may transfer heat to an airflow that is passed through and/or into contact with the indoor heat exchanger 108 by the indoor fan 110. After exiting the indoor heat exchanger 108, the refrigerant may flow through and/or bypass the indoor metering device 112, such that refrigerant flow is not substantially restricted by the indoor metering device 112. Refrigerant generally exits the indoor metering device 112 and flows to the outdoor metering device 120, which may meter the flow of refrigerant through the outdoor metering device 120, such that the refrigerant downstream of the outdoor metering device 120 is at a lower pressure than the refrigerant upstream of the outdoor metering device 120. From the outdoor metering device 120, the refrigerant may enter the outdoor heat exchanger 114. As the refrigerant is passed through the outdoor heat exchanger 114, heat may be transferred to the refrigerant from an airflow that is passed through and/or into contact with the outdoor heat exchanger 114 by the outdoor fan 118. Refrigerant leaving the outdoor heat exchanger 114 may flow to the reversing valve 122, where the reversing valve 122 may be selectively configured to divert the refrigerant back to the compressor 116, where the refrigeration cycle may begin again.

Alternatively, to operate the HVAC system 100 in a so-called cooling mode, most generally, the roles of the indoor heat exchanger 108 and the outdoor heat exchanger 114 are reversed as compared to their operation in the above-described heating mode. For example, the reversing valve 122 may be controlled to alter the flow path of the refrigerant from the compressor 116 to the outdoor heat exchanger 114 first and then to the indoor heat exchanger 108, the indoor metering device 112 may be enabled, and the outdoor metering device 120 may be disabled and/or bypassed. In cooling mode, heat may generally be absorbed by refrigerant at the indoor heat exchanger 108 and rejected by the refrigerant at the outdoor heat exchanger 114. As the refrigerant is passed through the indoor heat exchanger 108, the indoor fan 110 may be operated to move air into contact with the indoor heat exchanger 108, thereby transferring heat to the refrigerant from the air surrounding the indoor heat exchanger 108. Additionally, as refrigerant is passed through the outdoor heat exchanger 114, the outdoor fan 118 may be operated to move air into contact with the outdoor heat exchanger 114, thereby transferring heat from the refrigerant to the air surrounding the outdoor heat exchanger 114.

Referring now to FIG. 2, a schematic diagram of an air handling unit 200 is shown according to an embodiment of the disclosure. The air handling unit 200 may generally be configured as the indoor unit 102 or the outdoor unit 104 of FIG. 1. In addition, the air handling unit 200 may include a blower assembly 202 that is substantially similar to the indoor fan 110 or the outdoor fan 118 of FIG. 1. According to some aspects, the blower assembly 202 may be selectively removable from the air handling unit 200. The blower assembly 202 may generally comprise an electrically powered, motor driven rotatable blower that may be configured to deliver an airflow 230 through the air handling unit 200 in a downstream direction 236. In other aspects, the blower assembly 202 may be configured and/or repositioned to deliver an airflow in an upstream direction.

The air handling unit 200 may include a heat exchanger assembly 204 disposed downstream from the blower assembly 202. In other implementations, the heat exchanger assembly 204 may be disposed above the blower assembly 202, which may supply similar airflow by drawing air in the downstream direction 236. The heat exchanger assembly 204 may generally be configured as and/or employed as the indoor heat exchanger 108 or the outdoor heat exchanger 114 of FIG. 1. The heat exchanger assembly 204 may be disposed within a fluid duct of the air handling unit 200 and may also be selectively removable from the air handling unit 200.

In the implementation depicted in FIG. 2, the heat exchanger assembly 204 comprises a first slab 206 and a second slab 208 arranged to define an “A-coil” or “A-frame” heat exchanger assembly 204. However, it is to be understood that the first and second slabs 206, 208 may be arranged to define any suitable type of heat exchanger such as, but not limited to, a W-coil (“W-frame”), M-coil (“M-frame”), N-coil (“N-frame”), inverted N-Coil (“inverted N-frame”), V-coil (“V-frame”), etc. It is also to be understood that the heat exchanger assembly 204 may comprise more or less slabs in other implementations.

The first and second slabs 206, 208 generally comprise a plurality of tubes 210 arranged in one or more rows and disposed longitudinally through a plurality of adjacently disposed fins 212. The plurality of longitudinally finned tubes 210 and/or fins 212 are generally configured to carry a refrigerant, gas, liquid, and/or other suitable heat transfer medium configured to exchange heat with an airflow 230 passing between adjacent tubes 210 and/or adjacent fins 212. The tubes 210 and/or the fins 212 may generally be constructed of copper, stainless steel, aluminum, and/or another suitable material suitable for promoting heat transfer between the heat exchange medium carried within the tubes 210 and the airflow 230.

In some embodiments, one or more tubes 210 may extend through and beyond a fin 212 located at each end of the heat exchanger assembly 204 and be joined in fluid communication with one or more tubes 210. For example, the tubes 210 may be joined by a hairpin joint and/or U-joint to form a fluid circuit through the heat exchanger assembly 204. In other embodiments, the tubes 210 may be arranged in a plurality of parallel flow-paths and connected at each end of the heat exchanger assembly 204 by one or more headers to form a fluid circuit through the heat exchanger assembly 204.

The plurality of longitudinally finned tubes 210 are generally arranged in rows such that a first row 201 of tubes 210 directly receives the airflow 230 coming from the primary airflow direction 236 without first contacting another tube 210 not in that first row 201 of tubes 210. As such, an adjacent second row 203 of tubes 210 may receive the airflow 230 after passing between and/or contacting adjacently located tubes 210 in the first row 201, while a third row 205 of tubes 210 may receive the airflow 230 after passing between and/or contacting adjacently located tubes 210 in the second row 203. Additionally, while the heat exchanger assembly 204 is depicted as comprising three rows, in some embodiments, the heat exchanger assembly 204 may comprise as few as one row or any number of additional rows as a result of the size and/or other design criteria of the heat exchanger assembly 204.

In some embodiments, the air handling unit 200 may comprise at least one drain pan 250 disposed at a lower end 226 of the heat exchanger assembly 204. The air handling unit 200 may also comprise at least one baffle 216 disposed at an upper end 228 of the heat exchanger assembly 204. The lower end 226 of the heat exchanger assembly 204 may include a first tapered end 222, while the upper end 228 may include a second tapered end 224. In other implementations, however, the first end 222 and/or the second end 224 of the heat exchanger assembly 204 may not be tapered.

As shown in FIG. 2, each drain pan 250 is disposed substantially below the heat exchanger assembly 204 so that as condensation forms on and drips from the first and second slabs 206 and 208, the airflow 230 directs condensation into the drain pan 250. Each drain pan 250 may generally extend along the tapered end 222 and form a concavity 213 in the lower portion of the drain pan 250 that extends around the lower end 226 and vertically along an axis that is substantially orthogonal to the lower end 226. The concavity 213 may generally be configured to catch and/or receive condensate that may form on the tubes 210 and/or the fins 212 (e.g., as water vapor condenses when the air handling unit 200 generates a supply of cool air). In some embodiments, the drain pan 250 may comprise a channel, tube, and/or plurality of tubes for carrying away condensate from the concavity 213 of the drain pan 250. Additionally, the air handling unit 200 may comprise one or more drain pipes (not shown) configured to drain condensate from the concavity 213 in the drain pan 250.

Referring now to FIG. 3, a schematic diagram of an air handling unit 300 is shown according to another embodiment of the disclosure. The air handling unit 300 may generally be similar to that the air handling unit 200 of FIG. 2, except the fan assembly 302 and the heat exchanger assembly 304 in FIG. 3 are configured according to a horizontal application such that air primarily flows through the heat exchanger assembly 304 in a horizontal direction 336. In addition, the air handling unit 300 may include at least one drain pan 350 different than the at least one drain pan 250 of FIG. 2. Other than the foregoing distinctions, the air handling unit 300 may comprise substantially similar components as the air handling unit 200 of FIG. 2. Accordingly, the prior discussion of such components is similarly applicable and not repeated here for brevity. Further, while two drain pans 350 are depicted in FIG. 3, it is to be understood that the air handling unit 300 may include more or less drain pans 350 in other implementations. It is also to be understood that the air handling unit 300 may include one or more drain pipes (not shown) configured to drain condensate from a concavity 313 formed in the drain pan 350.

The drain pans 250, 350 in FIGS. 2 and 3 may generally be constructed from any suitable material such as, but not limited to, plastic. As previously discussed, plastic drain pans tend to be somewhat hydrophobic. Therefore, water droplets sitting in areas of a plastic drain pan exposed to high velocity may be swept up and propelled downstream. One or more solutions may be employed to address this “water blow-off” issue. For example, one solution may entail minimizing wet parts of a drain pan exposed to air streamlines. Another solution may entail modifying parts of a drain pan to include extensions configured to catch detached water droplets and return those droplets to the drain pan. However, these solutions often add production cost and can degrade system efficiency by restricting airflow. Moreover, these solutions may not adequately prevent water from being blown off a drain pan and transferred downstream or upstream (e.g., according to airflow direction).

As discussed further below, embodiments of the present disclosure may overcome these and other drawbacks by configuring the drain pans 250, 350 with at least one striated surface such that condensate quickly drains, e.g., without being exposed to high velocity airflow. Briefly, for example, FIG. 4 depicts an example of the effect airflow has on a water droplet 405 sitting on a flat surface of a conventional drain pan versus the effect airflow has on a water droplet 410 sitting on at least one striated surface of a drain pan as disclosed herein (e.g., drains pans 250 and 350). In both cases, the contact angle between the water droplet 405, 410 and drain pan surfaces is about 90 degrees. However, the water droplet 405 sitting on the flat surface of a conventional drain pan is more likely to be swept off by high velocity airflow, whereas the water droplet 410 sitting on the striated surface of drain pan 250 or 350 is less likely to be swept off because the water droplet 410 is directed beneath the peaks of the striated surface while the high velocity airflow remains above the peaks.

Referring now to FIG. 5, a schematic diagram of the drain pan 250 in FIG. 2 is shown according to an embodiment of the disclosure. The drain pan 250 may comprise at least a first fluted surface 255 defining a plurality of narrow striations 260 (e.g., parallel grooves) configured to collect condensation dripping from the heat exchanger assembly 204 and direct such condensation into a channel 265 within the drain pan 250. In some aspects, the channel 265 may be configured to fluidly cooperate with the concavity 213 in FIG. 2. In other aspects, the channel 265 may comprise the concavity 213 itself. The drain pan 250 may further comprise at least one opening 270 configured to drain collected condensation from the channel 265 of the drain pan 250 and into a drain pipe (not shown) coupled to the drain pan 250.

According to some implementations, the drain pan 250 may include at least a second fluted surface 275 defining a plurality of striations 280 substantially similar to the striations 260 on the first fluted surface 255, except the dimensions of the striations 260, 280 may differ from one another. For example, the dimensions of the striations 260, 280 may be individually designed to enhance overall performance of the drain pan 250. Moreover, the first and second fluted surfaces 255, 275 may be sloped at same or different angles (e.g., 30 degrees, 45 degrees, etc.) to promote the flow of condensate from the striations 260, 280 and into the channel 265.

In general, the striations 260, 280 on the drain pan 250 may be oriented so as to reduce and/or prevent water blow-off at areas downstream of an A-coil heat exchanger such as the heat exchanger assembly 204 of FIG. 2, as these areas may be more susceptible to water blow-off than other areas. However, the striations 260, 280 and/or the drain pan 250 may be repositioned or modified to reduce/prevent water blow-off at one or more other areas of the heat exchanger assembly 204. Similarly, while the drain pan 250 in FIG. 5 may generally be intended for an A-coil or V-coil heat exchanger, the drain pan 250 may be configured to accommodate any suitable type of heat exchanger. For example, the plurality of striations 260 and/or 280 on the drain pan 250 may be reoriented to collect condensate from any area(s) of a heat exchanger that may be particularly susceptible to water blow-off (e.g., due to high-velocity airstreams).

The drain pan's 250 ability to effectively drain condensed water (i.e., without being swept by high velocity airflow) may depend upon one or more dimensions of the striations 260, 280 such as, but not limited to, their width, depth, and/or curvature. In an embodiment, the plurality of striations 260, 280 may be dimensionally optimized to encourage the flow of condensation in a desired direction (e.g., toward the channel 265) such that under normal conditions, condensate may drain from the striations 260, 280 quickly enough that condensate does not overflow and protrude into high velocity airstreams. To this end, various factors may be taken into consideration such as, but not limited to, droplet size, droplet volume, contact angle, airflow velocity, gravitational force, drag force, adhesive force, drain force, etc.

In an embodiment, the striations 260, 280 may comprise semi-elliptical grooves open on their minor axes with minimal separation between the grooves. The grooves 260, 280 may comprise semi-elliptical cross sections of approximately 2:1 ellipses such that the depth of each groove 260, 280 is approximately equal to its maximum width, with this width typically being at the top of the groove 260, 280. This width may optimally be the characteristic maximum droplet height as calculated from the following equation:

${h = \sqrt{2*\gamma*\frac{1 - {\cos (\alpha)}}{g*\rho}}},$

where h is droplet height, γ is the surface tension of the liquid droplet, α is the contact angle of the droplet on the surface, g is the acceleration of gravity, and ρ is the liquid density. In the typical application of water droplets in air resting on a non-polar surface, this height h may be about 0.15 inches.

In some implementations, the plurality of striations 260, 280 may comprise parabolic-shaped grooves defining peaks and valleys such that water droplets dripping onto the fluted surfaces 255, 275 remain beneath the peaks of the grooves 260, 280 while air velocity streamlines remain above the peaks. According to one example, the grooves 260, 280 may define peaks between about 0.5 and 5 times the maximum droplet height (which may be calculated based on fluid and contact angle) and peak heights between about 0.5 and 2 times the maximum droplet height. Additionally or alternatively, the grooves 260, 280 may define curves having an inverse profile of a water droplet.

Referring now to FIG. 6A, a schematic diagram of the drain pan 350 in FIG. 3 is shown according to an embodiment of the disclosure. The drain pan 350 may comprise at least one fluted surface 355 defining a plurality of narrow striations 360. As shown in FIG. 6B, the striations 360 may comprise parallel grooves configured to collect condensation dripping from the heat exchanger assembly 304 and direct such condensation into a channel 365 within the drain pan 350. Moreover, the fluted surface 355 may be sloped at an angle (e.g., 30 or 45 degrees) to promote the flow of condensate from the striations 360 and into the channel 365. In some aspects, the channel 365 may be configured to fluidly cooperate with the concavity 313 in FIG. 3. In other aspects, the channel 365 may comprise the concavity 313 itself. The drain pan 350 may further comprise at least one opening 370 configured to drain collected condensation from the channel 365 of the drain pan 350 and into a drain pipe (not shown) coupled to the drain pan 350.

In general, the striations 360 on the drain pan 350 may be oriented so as to reduce and/or prevent water blow-off at areas downstream of a horizontal-type heat exchanger such as the heat exchanger assembly 304 of FIG. 3, as these areas may be more susceptible to water blow-off than other areas. However, the striations 360 and/or the drain pan 350 may be repositioned or modified to reduce/prevent water blow-off at one or more other areas of the heat exchanger assembly 304. Similarly, while the drain pan 350 in FIG. 6A may generally be intended for a horizontal-type heat exchanger, the drain pan 350 may be configured to accommodate any suitable type of heat exchanger. For example, the plurality of striations 360 on the drain pan 350 may be reoriented to collect condensate from any area(s) of a heat exchanger that may be particularly susceptible to water-blow-off (e.g., due to high-velocity airstreams).

Like the drain pan 250 in FIG. 5, the ability to effectively drain condensed water may depend upon one or more dimensions of the striations 360, e.g., width, depth, curvature, etc. In an embodiment, the plurality of striations 360 may be dimensionally optimized to encourage the flow of condensation in a desired direction (e.g., toward the channel 365) such that under normal conditions, condensate may drain from the striations 360 quickly enough that condensate does not overflow and protrude into high velocity airstreams. To this end, various factors may be taken into consideration such as described above with respect to FIG. 5.

In an embodiment, the striations 360 may comprise semi-elliptical grooves open on their minor axes with minimal separation between the grooves. The grooves 360 may comprise semi-elliptical cross sections of approximately 2:1 ellipses such that the depth of each groove 360 is approximately equal to its maximum width, with this width typically being at the top of the groove 360. This width may optimally be the characteristic maximum droplet height as calculated from the following equation:

${h = \sqrt{2*\gamma*\frac{1 - {\cos (\alpha)}}{g*\rho}}},$

where h is droplet height, γ is the surface tension of the liquid droplet, α is the contact angle of the droplet on the surface, g is the acceleration of gravity, and ρ is the liquid density. In the typical application of water droplets in air resting on a non-polar surface, this height h may be about 0.15 inches.

In some implementations, the plurality of striations 360 may comprise parabolic-shaped grooves defining peaks and valleys such that water droplets dripping onto the fluted surface 355 remain beneath the peaks of the grooves 360 while air velocity streamlines remain above the peaks. According to one example, the grooves 360 may define peaks between about 0.5 and 5 times the maximum droplet height (which may be calculated based on fluid and contact angle) and peak heights between about 0.5 and 2 times the maximum droplet height. Additionally or alternatively, the grooves 360 may define curves having an inverse profile of a water droplet.

FIG. 7 is a graph 700 illustrating an example of the physics behind water blow-off on a drain pan comprising a substantially flat surface (i.e., without striations 260, 280, or 360). More specifically, the graph 700 shows the relationship of competing forces on a conventional drain pan sloped at 30 degrees to drain the water, swept with an air velocity of 10 meters per second (m/s), and with a contact angle of 90 degrees. Lines 710, 720, and 730 represent the three active forces: Fg, the gravitational force 710 pulling the water droplet into the drain pan; Fa, the adhesive force 720 holding the water droplet to the drain pan; and Fd, the drag force 730 of the water droplet in the airstream that is trying to sweep the water droplet from the drain pan. The final force is the drain force 740, which is the sum of the three preceding forces, Fg+Fa+Fd. In this graph 700, the drain force 740 is plotted against the right axis. The x-axis represents the droplet volume.

If the drain force 740 is positive, the water droplet will proceed into the drain pan as desired. If the drain force 740 is negative, the drag force 730 prevails, thus causing the water droplet to be blown-off. If the drain force 740 is zero, the adhesion force 720 prevails, thus causing the water droplet to remain stationary, neither draining into the pan nor being blown from it. It is apparent from the graph 700 that for small water droplet volumes, the adhesive force 720 easily prevails over the other two competing forces (Fg 710 and Fd 730). Therefore, these small water droplets remain stationary. Yet as the water droplets increase in volume, the three competing forces increase as well. As shown in the graph 700, the gravitational force 710 increases linearly; the adhesion force 720 increases at a slower, declining rate; and the drag force 730 increases at a much greater, but also declining, rate. At a droplet volume of about 0.0025 cubic inches (in³), the drag force 730 exceeds the sum of the adhesion and gravity forces (Fa 720 and Fg 710), thus causing the drain force 740 to become negative, in which case the water droplet is blown off from the drain pan.

FIG. 8 is a graph 800 similar to graph 700 in that the results of the graph 800 were obtained using the same drain pan under the same conditions as in graph 700, except the drain pan used in this example incorporated striations such as described above with respect to drain pans 250, 350. Like the gravitational force 710 in graph 700, the gravitational force 810 in graph 800 increases linearly as the water droplet volume increases. While the adhesion force 820 and drag force 830 also increase, it is apparent from the graph 800 that the adhesion force 820 is initially much greater than the drag force 830. At a droplet volume of about 0.0008 in³, the drag force 830 and adhesion force 820 stop increasing. Physically, this represents the point where one of the striations has filled vertically and additional water droplet volume goes into filling the groove axially. Finally, at a droplet volume of about 0.0045 in³, the gravitation force 810 exceeds the sum of the other two forces 820 and 830, thus causing the drain force 840 to become positive, in which case the water droplet proceeds into the drain pan 250 or 350 as desired.

At least one embodiment is disclosed and variations, combinations, and/or modifications of the embodiment(s) and/or features of the embodiment(s) made by a person having ordinary skill in the art are within the scope of the disclosure. Alternative embodiments that result from combining, integrating, and/or omitting features of the embodiment(s) are also within the scope of the disclosure. Where numerical ranges or limitations are expressly stated, such express ranges or limitations should be understood to include iterative ranges or limitations of like magnitude falling within the expressly stated ranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than 0.10 includes 0.11, 0.12, 0.13, etc.). For example, whenever a numerical range with a lower limit, R_(l), and an upper limit, R_(u), is disclosed, any number falling within the range is specifically disclosed. In particular, the following numbers within the range are specifically disclosed: R=R_(l)+k*(R_(u)−R_(l)), wherein k is a variable ranging from 1 percent to 100 percent with a 1 percent increment, i.e., k is 1 percent, 2 percent, 3 percent, 4 percent, 5 percent, . . . , 50 percent, 51 percent, 52 percent, . . . , 95 percent, 96 percent, 97 percent, 98 percent, 99 percent, or 100 percent. Unless otherwise stated, the term “about” shall mean plus or minus 10 percent of the subsequent value. Moreover, any numerical range defined by two R numbers as defined in the above is also specifically disclosed. Use of the term “optionally” with respect to any element of a claim means that the element is required, or alternatively, the element is not required, both alternatives being within the scope of the claim. Use of broader terms such as comprises, includes, and having should be understood to provide support for narrower terms such as consisting of, consisting essentially of, and comprised substantially of. Accordingly, the scope of protection is not limited by the description set out above but is defined by the claims that follow, that scope including all equivalents of the subject matter of the claims. Each and every claim is incorporated as further disclosure into the specification and the claims are embodiment(s) of the present invention. 

What is claimed is:
 1. An air handling unit, comprising: at least one heat exchanger; and a drain pan disposed at least partially around a downstream end of the at least one heat exchanger, wherein the drain pan comprises a fluted surface configured to direct condensate flowing from the at least one heat exchanger into a concavity within the drain pan.
 2. The air handling unit of claim 1, wherein the fluted surface defines a plurality of narrow striations extending in the direction of condensate flowing into the concavity.
 3. The air handling unit of claim 2, wherein the plurality of narrow striations comprise parabolic-shaped grooves arranged substantially in parallel with one another.
 4. The air handling unit of claim 1, wherein the fluted surface defines peaks and valleys sized to keep condensate beneath the peaks of the fluted surface.
 5. The air handling unit of claim 1, wherein the fluted surface is sloped such that when a droplet of condensate contacts the fluted surface, gravitation forces acting on the droplet of condensate in the direction of the concavity are stronger than that those that would act on the droplet if on a flat surface instead of on the fluted surface.
 6. The air handling unit of claim 1, further comprising a blower assembly configured to supply a primary airflow in a downstream direction such that air passes through the at least one heat exchanger before reaching the drain pan.
 7. The air handling unit of claim 6, wherein the fluted surface defines a plurality of grooves having a curvature such that forces of adhesion and gravity prevent air flowing above the drain pan from blowing condensate off of the fluted surface.
 8. The air handling unit of claim 6, wherein the blower assembly and the at least one heat exchanger are disposed within the air handling unit such that the primary airflow travels in the downstream direction horizontally.
 9. The air handling unit of claim 1, wherein the at least one heat exchanger comprises two heat exchangers configured in an A-coil arrangement or a V-coil arrangement.
 10. The air handling unit of claim 9, wherein the drain pan comprises a second fluted surface above the fluted surface, each fluted surface being configured to direct condensate flowing from one of the heat exchangers into the concavity.
 11. A heating, ventilation, and/or air conditioning (HVAC) system, comprising: at least one heat exchanger; and a drain pan disposed at least partially around a downstream end of the at least one heat exchanger, wherein the drain pan comprises a fluted surface configured to direct condensate flowing from the at least one heat exchanger into a concavity within the drain pan.
 12. The HVAC system of claim 11, wherein the fluted surface defines a plurality of narrow striations extending in the direction of condensate flowing into the concavity.
 13. The HVAC system of claim 11, wherein the plurality of narrow striations comprise parabolic-shaped grooves arranged substantially in parallel with one another.
 14. The HVAC system of claim 11, wherein the fluted surface defines peaks and valleys sized to keep condensate beneath the peaks of the fluted surface.
 15. The HVAC system of claim 11, wherein the fluted surface is sloped such that when a droplet of condensate contacts the fluted surface, gravitation forces acting on the droplet of condensate in the direction of the concavity are stronger than that those that would act on the droplet if on a flat surface instead of on the fluted surface.
 16. The HVAC system of claim 11, further comprising a blower assembly configured to supply a primary airflow in a downstream direction such that air passes through the at least one heat exchanger before reaching the drain pan.
 17. The HVAC system of claim 16, wherein the fluted surface defines a plurality of grooves having a curvature such that forces of adhesion and gravity prevent air flowing above the drain pan from blowing condensate off of the fluted surface.
 18. The HVAC system of claim 16, wherein the blower assembly and the at least one heat exchanger are disposed within an air handling unit such that the primary airflow travels in the downstream direction horizontally.
 19. The HVAC system of claim 16, wherein the at least one heat exchanger comprises two heat exchangers configured in an A-coil arrangement or V-coil arrangement.
 20. The HVAC system of claim 19, wherein the drain pan comprises a second fluted surface above the fluted surface, each fluted surface being configured to direct condensate flowing from one of the heat exchangers into the concavity. 